1. Field of the Invention
This invention relates to hydrocarbon fuels, containing additives which reduce the deposit tendency of hydrocarbon fuels. More specifically, this invention discloses motor fuels obtained by the addition of a minor amount of an alkenylsuccinyl (polycarbonate polyglycolethyleneoxy)-B-hydroxypropionate.
As automobile manufacturers increase the compression ratio of their automobile engines to obtain higher horsepower, the need becomes greater for gasolines which burn cleanly and have low deposit forming tendencies. Engine deposits which find their origin in the fuel are primarily responsible for surface ignition phenomena such as pre-ignition and octane requirement increase (ORI) which is the tendency of increasing octane requirement during the first several thousand miles of operation. Basically this octane requirement increase is caused by deposits building up in the engine's combustion chambers which can cause engine `knock` or `ping`. Formally, knock or ping was stopped by either de-tuning the car's engine or by changing to a higher octane gasoline. The combustion chamber deposits also can cause engine run-on which is the sputter and clatter that is heard sometimes after an engine has been turned off. The present invention seeks to reduce the building up of deposits in an engine's combustion chamber so as to reduce engine knock and run-on and avoid octane requirement increases requiring the switch to a premium grade of gasoline.
2. Patent Information Disclosure
The most relevant art is constituted by coassigned U.S. Pat. No. 2,844,448 which relates to hydrocarbon fuels containing polyglycol carbonate esters to reduce the deposit-forming tendencies of such fuels. These polyglycol carbonate esters have the general formula EQU R'00C0(R0).sub.n C00R"
wherein R is a divalent aliphatic radical containing at least two carbon atoms, R' and R" are aliphatic hydrocarbons containing between 3 and 18 carbon atoms and n is an integer having a value of at least two. While these compounds are denominated in the patent "polycarbonates", the synthesis by which they are obtained can only lead to bis-carbonates and indeed all the examples in the patent are of bis-carbonates. The efficacy of the polyglycol carbonate esters in controlling the deposit-forming tendencies of motor fuels was demonstrated in the patent by a Modified Chevrolet Deposits Test - CRCFL - 2-650. The engine cleanliness was determined by a modified Chevrolet S-II test. The octane requirement increase was determined in the patent by the Lauson H-2 ORI Test Procedure. These tests were in current use in the 1940s and in the early 1950s using engines which are far different in octane requirements from present day engines. While fuels containing the bis-carbonates of the patent passed the above three mentioned tests they do not pass tests designed for present-day engines.